The presently disclosed subject matter relates to a method and apparatus for measuring the liquid level of a cell culture solution stored in a cell vessel.
As a method of determining whether a predetermined amount of a cell culture solution is dispensed to a cell vessel, there is a method in which a change in weight of a cell vessel is measured by using an electric balance. Also, there is another method in which an optical sensor that includes a light emitter and a light receiver is disposed and which uses a phenomenon that, when the liquid level reaches a predetermined level, the intensity of received light is changed (see, for example, JP-A-2003-294514).
An electric balance requires a bulky casing and is expensive. Its measurement value is changed even by a small air flow produced in a measurement space. In the case of the method in which an optical sensor is used, in order to detect plural kinds of liquid levels, it is necessary to dispose optical sensors the number of which is equal to that of the liquid levels. Therefore, the size and cost of a measuring apparatus are unavoidably increased, and the detectable liquid level is inevitably discrete.